Outbreak of Viral Hepatitis A in Murmansk City
Published: 18.11.04 Updated: 18.11.2004 14:56:26
A.V. Chernev, E.A. Matsievskaya, N.G. Perederij
State Sanitary and Epidemiological Centers of Murmanskaya Oblast and the City of Murmansk
Thirty-six cases of viral hepatitis A were notified in Murmansk from January 26 to March 1, 2000. 67% of the cases were among school-children, teenagers and young adults. The course of disease was medium to severe in 80% of the cases. There was found no association between food factor and intravenous drug use, but indirect evidence of fecal tap water pollution. Hepatitis A virus was not found in the tap water. Drinking tap water prior to boiling was a common factor in 19 of the 36 cases. After disinfection of the city water-supply system the viral hepatitis A incidence rate was reduced to a sporadic level.
During the last ten years the incidence rate of acute viral hepatitis A in Murmansk city has decreased considerably. There was a reduction from the maximum level of 210 cases per 100 000 population in 1990 to 1.9 in 1999. In 1999, only seven cases of hepatitis A were reported in Murmansk city, the capital of the Murmansk region of the Russian Federation.
Thirty-six cases of acute viral hepatitis A were registered in Murmansk from January 26 to March 1, 2000, with half of the infections occurring between January 15 and 22. Two thirds of cases were among schoolchildren, teenagers and youth (0-2 years of age, 1 case; 3-6 years of age, 1 case; 7-14 years of age, 7 cases; 15-19 years of age, 7 cases; 20-29 years of age, 10 cases; 30-39 years of age, 7 cases and 40 years of age, 3 cases). Two thirds of those taken ill were females. A typical acute onset and cholestatic syndrome were the clinical characteristics of the disease. The course of disease was medium to severe in approximately 80% of the cases.
There was no association between the registered infections and working place, organised groups, and place of eating meals or food supply. The use of intravenous drugs was considered to be a possible factor of viral hepatitis A transmission because the outbreak coincided with an increase in drug abuse among the youth in Murmansk. However, none of the infected used intravenous drugs. Drinking tap water prior to boiling was a common factor in 19 of the 36 cases.
Inhabitants of Leninski District of Murmansk city were the first to become ill. In this district the city receives water from the Tuloma River whereas water supplied to the district is from the Tuloma River and the Bolshoe Lake. Three households in the Leninski district each had two simultaneous cases during the first week of increasing incidence. The possibility of disease transmission through the water was therefore investigated.
No faults in the water supply or drainage system were registered in Murmansk from September 1999 to January 2000. During 1999 a number of water tests were performed. In 2.4% of the investigations water in the distributing pipe did not meet standard requirements for the microbiological indexes, and in 5.5 % of the analyses the water did not satisfy the physical-chemical requirements. Hepatitis A virus has not been found in the tap water or water supply sources for many years. However, the methods of investigation that are available in practice are not optimal.
According to the information given by the operating service, the water supply network serving 60 % of the homes is out-dated. The water is frequently switched off due to necessary repairs leading to a pressure reduction in the distribution network. As a result sewage water inflow appears at the joints of worn out pipes. This is most evident in the old houses that have cellars filled with water. On February 15, 2000, Escherichia coli was found in one of the tap water samples taken from an apartment of those who were ill, thus providing indirect evidence of fecal water pollution.
Measures to prevent the spread of viral hepatitis A were directed to improving the water quality. Disinfection of the city water-supply system and hyperchlorination of tap water with residual chlorine 1.5 mg/l were being maintained during the month, and water was siphoned from the cellars. Through the mass media, the population of the city was advised to boil drinking water. Following these measures the incidence rate was reduced to a sporadic level.